Viscurometer

ABSTRACT

A method and apparatus for determining the physical properties of vulcanizable elastomeric materials utilizing a cone-shaped oscillating rotor that is cooperative with a cone-shaped cavity in a stationary mold section whereby a sample of material is confined therebetween and subjected to a confining pressure, as well as an oscillating shearing force. The walls of the test chamber are heated to a predetermined temperature during cure, while torque sensing means are connected to the input of the rotor to measure the variation in force required to oscillate such projection. Means are provided to maintain a programmed confined pressure which increases linearly during the cure cycle permitting gradual closure of the stator and rotor rubber filled cavity compensating for any shrinkage of the sample. A recorder is connected to the torque sensing device to record the variations in shearing strain.

nited States atent Karper et a1.

[ 1 Sept. 5, 1972 Primary Examiner-Richard C. Oueisser AssistantExaminer-Marvin Smollar Attorney-Joseph Januszkiewicz and W. A. Shira,Jr.

[ 5 7 ABSTRACT A method and apparatus for determining the physicalproperties of vulcanizable elastomeric materials utilizing a cone-shapedoscillating rotor that is cooperative with a cone-shaped cavity in astationary mold section whereby a sample of material is confinedtherebetween and subjected to a confining pressure, as well as anoscillating shearing force. The walls of the test chamber are heated toa predetermined temperature during cure, while torque sensing means areconnected to the input of the rotor to measure the variation in forcerequired to oscillate such projection. Means are provided to maintain aprogrammed confined pressure which increases linearly during the curecycle permitting gradual closure of the stator and rotor rubber filledcavity compensating for any shrinkage of the sample. A recorder isconnected to the torque sensing device to record the variations inshearing strain.

16 Claims, 8 Drawing Figures PATENTED E 5 SHEET 1 [IF 6 INVENTORY; PAULW. KARPER JOHN P.POR'TER BYW ATTY.

llllll'lllllll l l l I I I I I I I l lllll'llln SHEET 2 UP 6 l I IHHHPATTENTEMP' 5 m2 JOHN P PORTER BY Q4/7114 l AT T Y.

PATENTEMEP 5 19 2 3.688568 SHEET 6 BF 6 9-3 92 F Lng ang;

90 9/ AM J INVENTORS PAUL W. KARPER JOHN. P. PORTER ATTY.

BACKGROUND OF THE INVENTION This invention relates to a method and testinstrument of the viscurometer type which has refined control meanswhich provides a test result of a cure curve that compensates for theshrinkage within a test sample during cure.

In the manufacture of articles made of elastomeric material, as well asin the research of these materials, it is necessary to determine therate, extent of vulcanization and cure curve of these materials in orderto provide the processing engineer with accurate data and parameters forthe manufacture of these articles. It is necessary to provide anaccurate cure curve from which scorch time, reversion and optimum curetime are obtained in order to accurately predict the heat history of thecompound within accurate processing limitations. Heretofore testinstruments employed in obtaining cure curves failed to effectively takeinto account excessive flow and/or shrinkage within the sample duringcure. This is particularly significant since shrinkage alters the curecurve. A test instrument not able to detect or compensate for shrinkage,could provide output data which would indicate a point of maximum cure,when, in actuality, the sample of material had not yet reached its fullcure. With such results, shrinkage would provide spurious results and aprocessing engineer would improperly set his processing parameters. Tominimize shrinkage by making the sample of material smaller couldmaterially affeet the accuracy and one would not be able to obtain thenecessary reliable data for precise laboratory testing. To reduce theamplitude of stroke does not rectify the error as it reduces thesensitivity of the instrument which impairs its accuracy. Applicantsinvention fully recognizes the slippage phenomena and accurately recordsand depicts the cure curve, even though shrinkage occurs within thesample by so constructing the instrument as to maintain a true outputwhich accurately depicts the cure curve of the sample of material. Byoptimum cure time is meant the time to cure the compound at a giventemperature to give some optimum physical properties. Scorch time refersto the time of the onset of cure at a given temperature. In order toproperly establish controls over the manufacturing of items ofelastomeric material, it is necessary to provide a test instrument thatis reliable, versatile, sensitive and operative to quickly andaccurately predict the true cure curve of a sample, taking into accountshrinkage, and which instrument is able to accurately record thecapability of the processing compound.

SUMMARY OF THE INVENTION The present invention provides a method andtest instrument which accurately measures the dynamic properties ofelastomeric material and which records such properties as a cure curve.

The present invention contemplates the use of a pair of spaced memberswhich are cooperative to define a double coned receptacle for thereception of a test sample with one member stationary and the othermember being oscillated to provide a shearing force on the sample andwith means provided to maintain a programmed pressure between the spacedmembers which maintains intimate contact with the sample at all times.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view ofthe test instrument with a portion thereof shown in cross section.

FIG. 2 is a side elevational view of the test instrument.

FIG. 3 is a plan view of the connection between the drive wheels foroscillating the rotor.

FIG. 4 illustrates the electrical control circuit for the testinstrument.

FIG. 5 illustrates the hydraulic circuit for the test instrument.

FIG. 6 is a chart illustrating the output of the torque cell as modifiedby the control circuit.

FIG. 7 is a chart illustrating the output of the torque cell showing astandard cure curve as A wherein the sample is subjected to a constantconfining pressure and a controlled cure curve B wherein the output ofthe torque cell is modified by the control circuit.

FIG. 8 illustrates an electrical control circuit for modifying thecircuit of FIG. 5 wherein the scorch point initiates programmedpressure.

DETAILED DESCRIPTION Referring to the drawings wherein like referencecharacters designate like or corresponding parts throughout the severalviews, there is shown in FIG. 1 a base plate 10 having attached to itsrear end portion an upwardly extending back plate 11. Back plate 1 1 hasan upper bracket 12 and a lower elongated bracket 13 securedrespectively to the upper end and intermediate portion thereof. Bracket13 has a bore 14 located in the central portion thereof to receive acylindrical member 15, which member 15 has a cylindrical recess 16 witha conduit 18 which is adapted to be connected to a suitable pressuresource. Secured to the respective end portions of bracket 13 arecylinders 20 which have pistons 21 and downwardly extending piston rods22 respectively extending through bores 23 in the respective endportions of such bracket 13 for connection to a stator member or carriermember 25. Carrier member 25 has a conically shaped serrated recess orcavity 26 at its center portion which is adapted to receive a coneshapedserrated rotor 27 for a purpose to be described. Rotor 27 has a lip 28on its base portion for cooperation with the base of recess 26 to definea substantially closed cavity with a restrictive passageway thereby.Rotor 27, and lip 28, cooperate with the cylindrical recess 16 ofcylindrical member 15 to define a pressure dome 50 that is adapted tocommunicate with the cavity defined by recess 26 and rotor 27. Carriermember or stator member 25 is guided in its vertical upward and downwardmovement by a pair of spaced guide rods 29 which are secured to a baseplate 10 and bracket 13 respectively. Upper bracket 12 has a centralbore 30 which rotatably receives a shaft 31 journalled in a bushing 32for connection to a wheel member 33 for rotation therewith. As shown inFIGS. 2 and 3, one end of a crank member 34 is pivotably mounted bymeans of a movable pin 35 to wheel member 33. As seen in FIG. 3, wheelmember 33 has a plurality of pin-receiving index holes 36, each at adifferent radial spacing from the vertical axis of wheel 33. Aneccentric drive wheel 37 is mounted on an output shaft 38 of a variablespeed motor 40. The other end portion of crank member 34 is pivotablymounted to such eccentric drive wheel 37 to transfer the rotationalmovement of shaft 38 to an oscillating motion in wheel 33 and shaft 31.The amplitude of the oscillation of wheel 33 is dependent upon theparticular mounting of pin 35 in index holes 36 of the wheel 33, whilethe frequency of oscillation is dependent upon the output speed of thevariable speed motor 40. If desired, such variable speed motor may beconnected to suitable transmission means which in turn may control thespeed of the output shaft 38. However, for simplicity of illustration,motor 40 is shown as directly connected to the output shaft 38.

Shaft 31 extends downwardly through a central bore 42 in cylindricalmember for connection to the cone rotor 27 to provide the oscillationthereto. Mounted on shaft 31 is a torque cell or torque sensing pickupdevice 43 which responds to torque forces in shaft 31 to provide aninput to a peak picker circuit, designated generally as 45via electricallines 46 and 47. Such circuit is disclosed in US. patent applicationSer. No. 774,958 filed Nov. 12, 1968, which circuit is incorporatedherein by reference The oscillating shearing forces developed on thesample of material are cyclically varying and generally sinusoidal innature and the peak picker circuit which includes a memory circuitprovides an output signal that is conveyed as a substantially linearsignal via electrical lines 48 and 49 to recorder 51. Recorder 51 has asuitable pen which graphically draws on its chart the torque values as afunction of time, depicted by FIGS. 6 and 7. Such pickup device 43 maycomprise a bonded resistance wire strain gauge, well known in the artand, therefore, neither illustrated nor described, wherein such wiregauges are bonded to the shaft 31 in such a position and are soconnected into a bridge circuit, that they cancel the effects of bendingand thrust strains, while adding the effects of torsional strain, withthe relation between bridge unbalance and torsional strain being linear.Such pickup devices are manufacture by the Baldwin- Lima-HamiltonCorporation, located in Waltham, Mass, and being known as type B torquepickup. Such devices are also manufactured by Lebow Associates, Inc.,located in Oak Park, Michigan; and being known as model 2 l 02-200.

The electrical power for the control operation is supplied by theelectrical lines 52 and 53 which are connected to a source of electricalpower not shown. A double pole, single throw switch 54 connects lines 52and 53 to main control lines or conductors 55 and 56 which lead to thetorque pickup recorder 51, as well as the temperature control means 57.Suitable branch lines not shown are provided to supply current from thecontrol means in a manner well known in the art to regulate the heatingcoils for the rotor 27 and the carrier member 25 to maintain apreselected temperature on the sample located between the cone-shapedcavity 26 and the cone rotor 27. Power is supplied from main controllines 52 and 53 via lines or conductors 55 and 56 to power supply unit60 which provides power via conductor 61 for an integrator and controlcircuit consisting of amplifier A-l, relay K-1, with contacts KIA andK113, capacitor C1, resistors R-l, R-2 and R-3. The output of theintegrator control circuit is conducted via conductor 62 to a currentcontrol circuit consisting of an amplifier A-2, transistor TR-l,capacitor C-2 and resistors R-4, R-S, R-6, R-7, R-8, R-9, R-

l0, R-ll. An electric-to-pneumatic transducer 65 is shown in FIG. 4 andFIG. 5 as interposed between the resistor R-9 and the emitter e oftransistor TR-l. Electric-topneumatic transducer 65 transmits apneumatic output signal (FlG. 5) via conduit 66 to a booster relay 67,which output signal is proportional to a DC. milliampere input signalfrom transistor TR-l. The transducer 65 receives an electrical signaland transfers such output signal into a pneumatic output, Such devicesare available commercially as from Moore Products Company, Spring House,Pennsylvania. The transducer 65 is a force-balance instrument, whereinthe force of the output pressure balances the force produced on theoutput coil of the input current and a permanent magnet field such as totransfer a minute input in the range of 4-20 milliamps to a 3l5 psipneumatic output in the example to be illustrated.

FIG, 5 illustrates the pneumatic control system wherein cylinders 2020control the closing pressure of the stator member 25 on the sample ofmaterial confined between cavity 26 and rotor 27 as well as pro grammedpressures thereon in a manner to be described.

A source of pressurized fluid is conducted from a source indicatedgenerally as 70 via conduit 71 to a pressure regulator valve PR-l whichcan be set to provide a predetermined line pressure in conduits 73, 74and 75. For purposes of illustration, the line pressure in conduit 73 isset at 80 psi. Conduit 75 is connected via solenoid controlled valveSV-3 to pressure dome 50. Conduit 74 is connected via solenoid operatedvalve SV-l either to pressurize the rod end ofcylinders 20 via conduit76, or to exhaust via conduit 77 and solenoid operated valve SV-4.Conduit 73 is connected to a pressure regulator valve PR-2 whose outputis set at 20 psi, The output of pressure regulator valve PR-2 isconducted to electric-to-pneumatic transducer 65 whose output isconducted to booster relay 67 via conduit 66. Booster relay 67multiplies the pressure output from transducer 65 by a factor of sixtimes, such that the output 1 890 psi) from booster relay 67 to conduit78 is six times the output pressure (3l5 psi) from transducer 65.Conduit 78 controls the pressurization of the rod end of cylinders 20via solenoid operated valve SV- 2. Solenoid operated valves SV-4, SV-3and SV-Z as well as energization of relay K-l and motor 40, arecontrolled by limit switch LS-l (FIGS. 1, 2, 4 and 5) and switch SW-4.Limit switch LS-l is set to be actuated at approximately 0.030 inches ofmechanical closure of cone-shaped rotor 27 within cone-shaped recess 26.Prior to closure of limit switch LS-l, power line 55 is connected vialine 79 through normally open switches SW-2 and SW-3 to the solenoidSV-lA of solenoid operated valve SV-l. Upon closure of switches SW-2,SW-3 and energization of solenoid SV-lA, valve SV-l directs thepressurized fluid from source 70 to pressurize the rod end of cylinders20. Solenoid SV-lB of valve .SV-l is energized by depressing oractuating switch SW-4 which connects power line 55 via depressed switchSW-5 which action connects the pressurized source via conduit 74 and 77to the head end of cylinders 20.

The temperature control circuit for the stator 25 and rotor 27 areconditioned for operation along with the circuit for the recorder 51,peak picker circuit 45 and the torque cell 43 by closing switch 54.

With the rotor 27 separated and spaced from the cone-shaped cavity 26,the operator inserts a sample of material to be tested into the testcavity 26. The operator then depresses the push buttons for switchesSW-2 and SW-3 to energize solenoid SV-IA which connects the pressuresource 70 via conduit 71 through pressure regulator valve PR-l which isset at 80 psi) thence via conduit 74 to solenoid operated valve SV-lwhich directs the pressurized fluid to the rod end of cylinders viaconduit 76. Such action moves the carrier member upwardly towards aclosing position, until limit switch LS-l is actuated. The closingpressure, which is referred to as the primary pressure or firstpressure, is set at 80 psi of the example chosen) and is of sufficientvalue to effect a shaping and molding of the sample to the shape of themold and mold cavity. Prior to the actuation of limit switch LS-l, relayK-l is in the de-energized condition maintaining the voltage out of theintegrator at zero voltage. The variable resistor R-6 is adjusted toprovide a current through the transducer 65 which will result in aninitial secondary pressure or a second pressure of psi in conduit 78.Upon actuation of limit switch LS-l, solenoid SVlA is de-energized whilesolenoids of valves SV-2, SV-3, SV- 4 and relay K-l are energized.Energization of solenoid operated valve SV-3 connects the pressurizedfluid from source 70 and pressure regulator valve PR-l to the domechamber 50 which establishes dome pressure to prevent porosity duringcure. As an example, the dome pressure is set at 60 psi in the examplechosen. Energization of solenoid operated valve SV-4 connects conduits76 and 77 to exhaust, while energization of valve SV-2 connects thepressure source 70 via conduits 71, 73 and 75 to booster relay 67 whichdirects the pressure fluid via line 78, through valve SV-2 to the rodend of cylinders 20 at a reduced pressure as controlled by the secondarypreset pressure of 35 psi set by transducer 65 and relay 67. With theenergization of relay K-l, switch KIA is closed which in turn completesthe circuit to the integrator circuit which in turn will control theoutput of the electric-to-pneumatic transducer 65 which in turn controlsthe amount which booster 67 increases the line pressure therethrough tocylinders 20, which is referred to as the secondary or second pressurewhich is to increase linearly. The pneumatic output of transducer 65 isproportional to the controlled input signal from the integrator circuit.As an example, the 4 to 20 milliamps input range of the integratorcircuit controls a 3-15 psi pneumatic output from transducer 65 forconduction to the multiplier or booster relay 67. Such action willprovide for a programmed increasing pressure, a continuous increase insecondary pressure.

Thus, prior to the closing of the rotor 27 on the test sample, theprimary pressure was 80 psi; however, on the closing of the rotor on thetest sample in cavity 26 to approximately 0.030 of an inch of completeclosure, the cylinders 20 exert a pressure as determined by the currentinput to transducer 65 and its control of relay 67 which is 35 psi, thesecondary pressure. The 35 psi, secondary pressure, may be extended fora controlled period of time such as 3 minutes by having relay K-loperating in conjunction with a time delay relay to delay the programmedpressure initiation or automatically as a function of scorch point asshown in FIG. 8. With relay K-l actuated, contact KIA is closed andcontact KIB is opened, whereby contact KIA connects the power supply 60to the input line of the integrator circuit. The applied voltage to theintegrator circuit is a function of the setting on the resistance R-Iand resistor R-2, which acts as a potentiometer or voltage dividercircuit. Output voltage of amplifier A-ll is the integral of the voltageas a function of time. With a constant input voltage, the voltage outputis linear as a function of time. With the opening of normally closedcontact KIB, the integrator circuit becomes operative whereby a currentI flows through resistor R-4 towards the summing junction in amplifierA-2. The current I,, through resistor R-7 is summed with I and invertedby amplifier A-2. The output voltage of amplifier A-2 increases inopposite polarity to the applied voltage on resistors R-4 and R-7 untilthe current through resistors R-ll and R-l0 is equal to the currentthrough R-4 and R-7 which is equal to I,, I,,. To accomplish this stablecondition, the output voltage of amplifier A-2 is applied to resistorR-8, resulting in a current being supplied to the base of transistorTR-l which transistor TR-l is connected in an emitter followerconfiguration to provide a current gain. The feedback to amplifier A- 2is established by the voltage applied to resistor R-9 which is afunction of the current through the coil of the electric-to-pneumatictransducer 65 (FIGS. 4 and 5). Resistors R-10 and R-ll provide thefeedback current path to the summing junction of amplifier A-2. Currentflows from the common terminal of the power supply 60 through resistorR-9, the coil of transducer 65 and the emitter to the collector oftransistor TR-l. until the voltage across resistor R-9 is sufficient toprovide the required current through resistors R-10 and R- 1 1. Thus,the current through the coil of transducer 65 is a function of theoutput voltage of the integrator and the initial condition set up byvariable resistor R-6. In a typical example, the current range of thecoil of transducer 65 is 0.004 amps to 0.020 amps; with the pneumaticoutput of transducer 65 being 3 to 5 psi; and the output range ofbooster relay 67 being 18 to psi. With the integrator circuit actuated,the secondary pressure increases linearly from 35 psi to a secondarypressure of 90 psi in 15 minutes in the typical example presented. It isto be understood that the pressures can be programmed to begin atpreselected different pressure, with the linear slope such as to achievea final secondary pressure that is different than 90 psi, as well aschange the time interval to achieve the final secondary pressure. Withthe initiation of the test cycle and the secondary pressure of 35 psibeing maintained for a preset time which in the example may be for 3minutes, relay K-l is actuated to start the pressure programmed circuit.The use of the term programmed pressures is for a logically consistentsequence of increasing pressures.

FIG. 8 illustrates the circuit modification of FIG. 4 wherein the scorchpoint is used to energize relay K-l to perform the same function as thecircuit of FIG. 4. Herein the voltage-time signal from the peak pickercircuit 45 is connected to a differentiating circuit which includescapacitor 90, amplifier 91 and resistor 92. A voltage output resultsfrom amplifier 91 except when the rate of change is zero, which in FIG.6 is point E, minimum torque from which point the scorch point is to bedetermined. For the example shown the scorch point is set at 3 unitsabove minimum torque value, which in FIG. 6 on curve D is approximately19 inch pounds of torque occurring at 7 minutes, designated as point F.The voltage from the differentiating circuit is applied to a zerocross-over detector 93. When a signal from the zero cross-over detector93 indicates a zero cross-over is present, gate 94 has a signal outputto cause the sample hold circuit 95 to operate. The voltage-time signalis put in memory.

A signal comparitor 96 compares the voltage from the sample hold circuit95 with the continuous voltage time signal. Voltage divider 97attenuates this signal to establish the arbitrary scorch point value,which in the example above is 3 units of torque above minimum value oftorque. When the voltage from voltage divider 97 exceeds that from thesample hold circuit 95, an output voltage occurs from the signalcomparitor 96, turning on transistor 98 to energize relay K-l andthereby initiate the programmed pressure cycle as described in detailabove.

FIG. 7 depicts the comparison of cure curves wherein the first samplewas cured without the use of the pressure programmer standard curve) andwherein such curve A had a primary closing pressure of 80 psi, which onclosure was reduced to 46 psi and maintained at such pressure for theentire test cure. Such material was cured at 340 F. Curve A reaches amaximum at approximately 5.5 minutes after initiation of the test cyclegiving a maximum torq ue reading of 70 inch pounds; whereas, a secondsample curve B) of the same material cured at 340 F. with the use of apressure programmer described above wherein the secondary pressure of 36psi is increased linearly at 4 psi per minute, the maximum torquedeveloped is 94 inch pounds in 6.75 minutes. Thus, where it appears asin curve A that full maximum cure has been developed and that reversionhas set in, it is disclosed by cure curve B that reversion in face hasnot set in. Thus, the margin of error is material. The furtherbeneficial effect of maintaining pressure is that the steepness does notfall off as rapidly on Curve B as Curve A, thus providing for greateraccuracy in measuring the different critical points on the cure curve.FIG. 6 illustrates cure curves C and D wherein there is provided a 3minute delay before the pressure is linearly increased. Cure curve C hasa primary pressure of 80 psi with a dome pressure of 60 psi and asecondary pressure of 36 psi. After a 3 minute delay, indicated as pointE on curve C, the pressure is increased at the rate of 2 psi per minuteuntil a maximum pressure of 82 psi is achieved, and thereafter themaximum pressure of 82 psi is maintained. Curve D has a flattening ofthe curve at approximately 98 inch pounds, and 95 percent of this givesan optimum cure of 93 inch pounds at 19 minutes from the initiation ofthe cycle.

CURE CURVE C Time Elapsed in Minutes amen-Jawbone- Such data indicatesthat the gap does change between the respective mold sections and thatwith the linear increase in secondary pressure, the cure curve iseffectively traced and compensates for shrinkage in the sample ofmaterial. Although curometers are good as control instruments to setlimits in production, such instruments do not effectively compensate forshrinkage and do not provide necessary available data as a researchinstrument where one is attempting to determine the various criticalpoints on a cure curve, wherein the compound is varied by as little as 5percent with respect to a single ingredient. Under ordinary conditionsof testing with the conventional instrument one would not be able todifferentiate between these batches where there is a mere 5 percentdifference in compounds. However, with the present instrument one isable to determine more accurately the scorch point and optimum curepoint. The reason for the delay in the timing for the increasing in thepressure is to allow the rubber or the sample of material to softensuffciently to accurately portray its softening and flowcharacteristics.

Although specific embodiments and a preferred mode of operation of theinvention has been hereinbefore described, it is understood that thesubject invention is not limited thereto since variations andmodifications thereof can be made without departing from the principlesof the invention.

We claim:

1. An apparatus for determining the physical properties of vulcanizableelastomeric material comprising a pair of die means cooperable to definea test sample receiving chamber with an annular opening between said diemeans and wherein said chamber receives a test sample, means connectedto one of said die means for oscillation thereof to provide a shearingforce on said sample in said test chamber, means operatively connectedto said oscillating means for measuring said shearing force andproviding an output signal therefrom, means to move the other of saiddie means relative to said one die means for cooperative engagement withthe sample to maintain a pressure on said sample held between said diemeans; a pressure dome providing a closure for said opening between saiddie means, means to supply pressurized fluid to said pressure dome undercontrolled pressure to maintain a preselected fluid pressure on a testsample confined in said test chamber, means to heat said die means to apredetermined temperature, indicator means operative to receive saidoutput signal for indicating its progressive value for use in analyzingsaid materials, and means operatively connected to said die moving meansto provide a primary pressure and a secondary controlled linearlyincreasing programmed pressure.

2. An apparatus as set forth in claim 1 wherein said die means arecooperative to define a hollow cone cavity with a restrictive openingalong the upper end portion of said hollow cone cavity, said die meansare cooperative with a housing to define said pressure dome thatcommunicates with said hollow cone cavity through said restrictiveopening, and said means for providing said controlled programmedpressure includes a linearly increasing programmed pressure to apredetermined pressure.

3. An apparatus as set forth in claim 2 wherein time delay means areoperatively connected to said means for providing said controlledprogram pressure to provide a preselected time interval after theinitiation of said secondary pressure to provide for said linearlyincreasing pressure.

4. An apparatus for determining the physical properties of vulcanizableelastomeric materials comprising a pair of spaced die members cooperableto define a test chamber and hold a sample of material therebetween;oscillating means operatively connected to one of said die members foroscillating said one die member relative to the other die member toprovide a shearing force on said sample received by said test chamber;measuring means operatively connected to said oscillating means formeasuring said shearing force and providing an output signal therefrom;means to heat said die members to a preselected temperature; meansoperative to receive said output signal for indicating its progressivevalue; air cylinder means operatively interconnecting said die membersto move said other die member toward said one member into cooperativeengagement with a test sample held in said test chamber to provide apressure thereon, control means connected to said air cylinder means toprovide a primary pressure followed by a secondary pressure wherein saidsecondary pressure is different than said primary pres sure; and saidsecondary pressure is a programmed to linearly increase to apredetermined pressure.

5. An apparatus for determining the physical properties of vulcanizableelastomeric material as set forth in claim 4 wherein said control meansincludes circuit means for providing a linearly increasing outputsignal, and booster means operative to receive said output signal andprovide as said secondary pressure a controlled increasing air pressureinput to said air cylinder means to provide said linear increasingpressure to a sample held in said test chamber during said secondaryprogrammed pressure.

6. An apparatus for determining the physical properties of vulcanizableelastomeric materials as set forth in claim 5 wherein said circuit meanshas a time delay means for holding said secondary pressure at a constantpressure for a predetermined time interval and thence linearlyincreasing said secondary pressure to said predetermined pressure.

7. An apparatus for determining the physical proper ties of vulcanizablematerials as set forth in claim 6 wherein said increasing pressure isset to reach a predetermined maximum pressure.

8. An apparatus for determining the physical properties of vulcanizablematerials as set forth in claim 7 wherein said time delay means delaysthe initiation of said linearly increasing output signal until scorchpoint is reached.

9. An apparatus for determining the physical properties of vulcanizableelastomeric materials comprising a pair of spaced die members cooperableto define a test chamber and hold a sample of material therebetween;oscillating means operatively connected to one of said die members foroscillating said one die member relative to the other die member toprovide a shearing force on said sample received by said test chamber;measuring means operatively connected to said oscillating means formeasuring said shearing force and providing an output signal therefrom;means to heat said die members; means operative to receive said outputsignal for indicating its progressive value; air cylinder meansoperatively interconnecting said die members to move said other diemember toward said one member into cooperative engagement with a testsample held in said test chamber to provide a pressure thereon, controlmeans connected to said air cylinder means to provide a primary pressurefollowed by a secondary pressure operative on said air cylinder means,and said control means includes circuit means for maintaining saidsecondary pressure at a constant pressure followed by a linearlyincreasing pressure to a predetermined pressure, and said circuit meansincluding means responsive to a minimum torque output signal from saidoutput signal to actuate said linearly increasing pressure following apreset time interval.

10. An apparatus for determining the physical properties as set forth inclaim 9 wherein said linearly increasing pressure is initiated at thescorch point.

11. An apparatus for determining the physical properties of vulcanizableelastomeric materials compris ing a pair of spaced die memberscooperable to define a test chamber and hold a sample of materialtherebetween; oscillating means operatively connected to one of said diemembers for oscillating said one die member relative to the other diemember to provide a shearing force on said sample received by said testchamber; measuring means operatively connected to said oscillating meansfor measuring said shearing force and providing an output signaltherefrom; means to heat said die members; means operative to receivesaid output signal for indicating its progressive value; air cylindermeans operatively interconnecting said die members to move said otherdie member toward said one member into cooperative engagement with atest sample held in said test chamber to provide a pressure thereon,control means connected to said air cylinder means to provide a primarypressure followed by a secondary programmed pressure, said control meansfor said programmed pressure to said air cylinders includes anintegrator circuit and a current control circuit, said integratorcircuit provides an increasing input signal to said current controlcircuit, a pneumatic booster relay operatively connected to said aircylinder means to provide an input thereto, an electric-to-pneumatictransducer operative in said control circuit to receive the output fromsaid current control circuit and to provide a control signal to saidpneumatic booster relay to incremental linearly increase the airpressure to said air cylinder means upon actuation of said secondarypressure, said secondary pressure being linearly increased to apredetermined pressure.

12. A method for determining physical properties of elastomericmaterials comprising: subjecting a sample of material to a firstconfining pressure, heating such sample to a predetermined temperaturethence subjecting said confined heated sample to oscillating shearingstrains from an input source having predetermined constant rate andamplitude of oscillation, measuring the torsional resistance to saidshearing strains, subjecting said sample of material to a secondpressure different than said first pressure which second pressure is acontrolled programmed pressure linearly increasing to a predeterminedmaximum.

13. A method for determining physical properties of elastomericmaterials as set forth in claim 12 wherein said second pressure is heldconstant for a predetermined period of time.

14. A method for determining physical properties of elastomericmaterials comprising: subjecting a confined sample of material to afirst pressure for a predetermined period of time, heating such sampleto a predetermined temperature, subjecting said confined heated sampleto oscillating shearing strain from an input source, subjecting saidsample of material to a secondary linear increasing confining pressureafter elapse of said predetermined time while being subjected to saidoscillating shearing strain; and measuring the torsional resistance tothese shearing strains.

15. The method for determining the physical properties as set forth inclaim 14 wherein said secondary pressure is for a predetermined timeinterval.

16. The method for determining the shearing torque as set forth in claim15 wherein said subjecting of said sample of material to said secondarypressure is after the scorch point of the material is reached.

a a a UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,688,568 Dated September 5, 1972 Inventor(s) Paul W. Karper, John P.Porter It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 7, line 38, the word "face" should be ---fact---.

Column 9, line 35, (Claim L delete [a].

Column 11, lines 6 and 7 (Claim 12), delete [linearly increasing to apredetermined maximum] Column 11, line 6 (Claim 12) before the word"pressure" insert ---linearly increasing to a predetermined maximum---.

Signed and sealed this 13th day of March 1973 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents DRM PO-105O (IO-69) USCOMM-DC 60376-F69 Q U.S4 GOVERNMENTPRINTING OFFICE: I969 O-3E6-334

1. An apparatus for determining the physical properties of vulcanizableelastomeric material comprising a pair of die means cooperable to definea test sample receiving chamber with an annular opening between said diemeans and wherein said chamber receives a test sample, means connectedto one of said die means for oscillatIon thereof to provide a shearingforce on said sample in said test chamber, means operatively connectedto said oscillating means for measuring said shearing force andproviding an output signal therefrom, means to move the other of saiddie means relative to said one die means for cooperative engagement withthe sample to maintain a pressure on said sample held between said diemeans; a pressure dome providing a closure for said opening between saiddie means, means to supply pressurized fluid to said pressure dome undercontrolled pressure to maintain a preselected fluid pressure on a testsample confined in said test chamber, means to heat said die means to apredetermined temperature, indicator means operative to receive saidoutput signal for indicating its progressive value for use in analyzingsaid materials, and means operatively connected to said die moving meansto provide a primary pressure and a secondary controlled linearlyincreasing programmed pressure.
 2. An apparatus as set forth in claim 1wherein said die means are cooperative to define a hollow cone cavitywith a restrictive opening along the upper end portion of said hollowcone cavity, said die means are cooperative with a housing to definesaid pressure dome that communicates with said hollow cone cavitythrough said restrictive opening, and said means for providing saidcontrolled programmed pressure includes a linearly increasing programmedpressure to a predetermined pressure.
 3. An apparatus as set forth inclaim 2 wherein time delay means are operatively connected to said meansfor providing said controlled program pressure to provide a preselectedtime interval after the initiation of said secondary pressure to providefor said linearly increasing pressure.
 4. An apparatus for determiningthe physical properties of vulcanizable elastomeric materials comprisinga pair of spaced die members cooperable to define a test chamber andhold a sample of material therebetween; oscillating means operativelyconnected to one of said die members for oscillating said one die memberrelative to the other die member to provide a shearing force on saidsample received by said test chamber; measuring means operativelyconnected to said oscillating means for measuring said shearing forceand providing an output signal therefrom; means to heat said die membersto a preselected temperature; means operative to receive said outputsignal for indicating its progressive value; air cylinder meansoperatively interconnecting said die members to move said other diemember toward said one member into cooperative engagement with a testsample held in said test chamber to provide a pressure thereon, controlmeans connected to said air cylinder means to provide a primary pressurefollowed by a secondary pressure wherein said secondary pressure isdifferent than said primary pressure; and said secondary pressure is aprogrammed to linearly increase to a predetermined pressure.
 5. Anapparatus for determining the physical properties of vulcanizableelastomeric material as set forth in claim 4 wherein said control meansincludes circuit means for providing a linearly increasing outputsignal, and booster means operative to receive said output signal andprovide as said secondary pressure a controlled increasing air pressureinput to said air cylinder means to provide said linear increasingpressure to a sample held in said test chamber during said secondaryprogrammed pressure.
 6. An apparatus for determining the physicalproperties of vulcanizable elastomeric materials as set forth in claim 5wherein said circuit means has a time delay means for holding saidsecondary pressure at a constant pressure for a predetermined timeinterval and thence linearly increasing said secondary pressure to saidpredetermined pressure.
 7. An apparatus for determining the physicalproperties of vulcanizable materials as set forth in claim 6 whereinsaid increasing pressure is set to reach a predetermined maximumpressure.
 8. An apparatus for deterMining the physical properties ofvulcanizable materials as set forth in claim 7 wherein said time delaymeans delays the initiation of said linearly increasing output signaluntil scorch point is reached.
 9. An apparatus for determining thephysical properties of vulcanizable elastomeric materials comprising apair of spaced die members cooperable to define a test chamber and holda sample of material therebetween; oscillating means operativelyconnected to one of said die members for oscillating said one die memberrelative to the other die member to provide a shearing force on saidsample received by said test chamber; measuring means operativelyconnected to said oscillating means for measuring said shearing forceand providing an output signal therefrom; means to heat said diemembers; means operative to receive said output signal for indicatingits progressive value; air cylinder means operatively interconnectingsaid die members to move said other die member toward said one memberinto cooperative engagement with a test sample held in said test chamberto provide a pressure thereon, control means connected to said aircylinder means to provide a primary pressure followed by a secondarypressure operative on said air cylinder means, and said control meansincludes circuit means for maintaining said secondary pressure at aconstant pressure followed by a linearly increasing pressure to apredetermined pressure, and said circuit means including meansresponsive to a minimum torque output signal from said output signal toactuate said linearly increasing pressure following a preset timeinterval.
 10. An apparatus for determining the physical properties asset forth in claim 9 wherein said linearly increasing pressure isinitiated at the scorch point.
 11. An apparatus for determining thephysical properties of vulcanizable elastomeric materials comprising apair of spaced die members cooperable to define a test chamber and holda sample of material therebetween; oscillating means operativelyconnected to one of said die members for oscillating said one die memberrelative to the other die member to provide a shearing force on saidsample received by said test chamber; measuring means operativelyconnected to said oscillating means for measuring said shearing forceand providing an output signal therefrom; means to heat said diemembers; means operative to receive said output signal for indicatingits progressive value; air cylinder means operatively interconnectingsaid die members to move said other die member toward said one memberinto cooperative engagement with a test sample held in said test chamberto provide a pressure thereon, control means connected to said aircylinder means to provide a primary pressure followed by a secondaryprogrammed pressure, said control means for said programmed pressure tosaid air cylinders includes an integrator circuit and a current controlcircuit, said integrator circuit provides an increasing input signal tosaid current control circuit, a pneumatic booster relay operativelyconnected to said air cylinder means to provide an input thereto, anelectric-to-pneumatic transducer operative in said control circuit toreceive the output from said current control circuit and to provide acontrol signal to said pneumatic booster relay to incremental linearlyincrease the air pressure to said air cylinder means upon actuation ofsaid secondary pressure, said secondary pressure being linearlyincreased to a predetermined pressure.
 12. A method for determiningphysical properties of elastomeric materials comprising: subjecting asample of material to a first confining pressure, heating such sample toa predetermined temperature thence subjecting said confined heatedsample to oscillating shearing strains from an input source havingpredetermined constant rate and amplitude of oscillation, measuring thetorsional resistance to said shearing strains, subjecting said sample ofmaterial to a second pressure different than said first pressure whichsecond Pressure is a controlled programmed pressure linearly increasingto a predetermined maximum.
 13. A method for determining physicalproperties of elastomeric materials as set forth in claim 12 whereinsaid second pressure is held constant for a predetermined period oftime.
 14. A method for determining physical properties of elastomericmaterials comprising: subjecting a confined sample of material to afirst pressure for a predetermined period of time, heating such sampleto a predetermined temperature, subjecting said confined heated sampleto oscillating shearing strain from an input source, subjecting saidsample of material to a secondary linear increasing confining pressureafter elapse of said predetermined time while being subjected to saidoscillating shearing strain; and measuring the torsional resistance tothese shearing strains.
 15. The method for determining the physicalproperties as set forth in claim 14 wherein said secondary pressure isfor a predetermined time interval.
 16. The method for determining theshearing torque as set forth in claim 15 wherein said subjecting of saidsample of material to said secondary pressure is after the scorch pointof the material is reached.